1. Field of the Invention
The present invention relates to an information processing apparatus and program, and more particularly to an information processing apparatus and program operable by a user using an input device including an imaging device.
2. Description of the Background Art
Conventionally, technologies for designating a specific position on a display screen using an optical pointing system have been proposed. For example, an optical pointing system described in Japanese Laid-Open Patent Publication No. 6-308879 is used for conferences or the like held for a plurality of viewers. According to this system, a light emitting element is provided in the vicinity of the display screen, and an imaging device using an optic/electric conversion element is built in an indicator. The user can designate an arbitrary position on the display screen using the indicator as follows. The indicator takes an image of the light emitting element by the imaging device and the position designated by the user is calculated based on the obtained image. A mark is displayed at the calculated position, and thus the designated position is indicated with the mark.
A game controller which uses an optical pointing system substantially the same as the above has been proposed (see, for example, Japanese Laid-Open Patent Publication No. 8-71252). The controller has a shape of a gun and is used for a shooting game. The shooting game is for shooting a target displayed on the screen with a gun. The gun is used for designating an arbitrary position (which the bullet is to hit) on the screen. The gun-shaped controller has a built-in CCD camera, and light emitting elements located at four positions around the screen are imaged by the CCD camera. The controller calculates the rotation angle or the inclining angle of the gun using the obtained images. The controller uses the calculation result to detect whether or not the gun is correctly directed toward the target displayed on the screen, and thus determines whether or not the bullet has hit the target. With such a structure, a game system by which the player performs a game operation by moving the controller (gun) held in his/her hand can be realized.
With the above-described technologies, the input device held in the user's hand (the indicator or the gun-shaped controller) is only used for designating a position on the display screen. Namely, the above-described indicator or gun-shaped controller allows the player to perform only one operation of designating a position on the display screen but not any other operation. For example, when used for a game apparatus, such an input device allows the player to perform only one simple game operation of designating a position on the display screen. Since the game operation is quite simple, the game itself is simple and is not entertaining.